400 Canadian Record of Science 



tant of water supplies, one part of copper to ten million 

 parts of water is sufficient to destroy Anabaena in ponds 

 and in reservoirs, while Oscillatoria requires one part of 

 copper in every five million parts of water, and forms 

 like Eudorina and Pandorina require one part of copper 

 in every one hundred thousand parts of water. 



The chief advantage of the potassium-copper-acetate 

 solution, which serves at once as a killing, fixing and pre- 

 serving solution, is the way in which it preserves the 

 delicate shades of the green algae. Material preserved 

 in this way may be mounted satisfactorily in glycerine- 

 jelly. I found the solution remarkably successful for 

 Desmids and the various species of Spirogyra. 



As well as securing forms for later identification, the 

 sample from each aquarium served as a valuable check 

 or control in studying the persistence or disappearance 

 of various forms, the normal habit, the periodicity, and 

 the appearance and development of those, whose spores 

 only had been gathered. 



Alg^e under Artificial Environment. 



On the field trips a number of small collecting bottles 

 were carried and each sample of algas secured from pool, 

 pond or wet bank was placed by itself in one. If several 

 samples were taken from the same large pond, they were 

 all put into separate bottles. On being brought into the 

 laboratory, the contents of each was placed in a separate 

 aquarium which was then filled up with water. Stones 

 and tufts of water-weed with algae attached were col- 

 lected and treated in the same way. By the end of 

 October some sixty-five aquaria, ranging in size from one 

 to ten liters, were set up, the majority having a capacity 

 of about three liters. In every case the water used was 

 the ordinary tap-water. The reports of various botanists 

 who have cultivated algae in water and in nutrient solu- 

 tions show that the results of tap-water cultures have 

 been distinctly variable. The variation naturally de- 



